1. Field of the Invention
The present invention relates generally to split internal combustion engines and, more specifically, to a double piston cycle engine (DPCE) that is more efficient then conventional combustion engines.
2. Description of the Related Art
Conventional internal combustion engines include one or more cylinders. Each cylinder includes a single piston that performs four strokes, commonly referred to as the intake, compression, combustion/power, and exhaust strokes. Together, these four strokes form a complete cycle of a conventional internal combustion engine.
Conventional internal combustion engines have low fuel efficiency—more than one half of the potential thermal energy created by conventional engines is estimated to dissipate through the engine structure and exhaust outlet, without adding any useful mechanical work. A major cause of thermal waste in conventional internal combustion engines is the essential cooling system (e.g., radiator), which alone dissipates heat at a greater rate and quantity than the total heat actually transformed into useful work. Furthermore, conventional internal combustion engines are unable to increase efficiencies by employing low heat rejection methods in the cylinders and pistons.
Further inefficiency results from high-temperature in the cylinder during the intake and compression strokes. This high temperature reduces engine volumetric efficiency, makes the piston work harder and, hence, reduces efficiency during these strokes.
Theoretically, a larger expansion ratio than compression ratio will greatly increase engine efficiency in an internal combustion engine. In conventional internal combustion engines, the expansion ratio is largely dependent on the compression ratio. Moreover, conventional means to make the engine expansion ratio independent of the compression ratio are inefficient.
Another problem with conventional internal combustion engines is an incomplete chemical combustion process, which reduces efficiency and causes harmful exhaust emissions.
Others have previously disclosed dual-piston combustion engine configurations. For example, U.S. Pat. No. 1,372,216 to Casaday discloses a dual piston combustion engine in which cylinders and pistons are arranged in respective pairs. The piston of the firing cylinder moves in advance of the piston of the compression cylinder. U.S. Pat. No. 3,880,126 to Thurston et al. discloses a two-stroke cycle split-cylinder internal combustion engine. The piston of the induction cylinder moves somewhat less than one-half stroke in advance of the piston of the power cylinder. The induction cylinder compresses a charge, and transfers the charge to the power cylinder where it is mixed with a residual charge of burned products from the previous cycle, and further compressed before igniting. U.S. Pat. Application No. 2003/0015171 A1 to Scuderi discloses a four-stroke cycle internal combustion engine. A power piston within a first cylinder is connected to a crankshaft and performs power and exhaust strokes of the four-stroke cycle. A compression piston within a second cylinder is also connected to the crankshaft and performs the intake and compression strokes of the same four-stroke cycle during the same rotation of the crankshaft. The power piston of the first cylinder moves in advance of the compression piston of the second cylinder. U.S. Pat. No. 6,880,501 to Suh et al. discloses an internal combustion engine that has a pair of cylinders, each cylinder containing a piston connected to a crankshaft. One cylinder is adapted for intake and compression strokes. The other cylinder is adapted for power and exhaust strokes. U.S. Pat. No. 5,546,897 to Brackett discloses a multi-cylinder reciprocating piston internal combustion engine that can perform a two, four, or diesel engine power cycle.
However, these references fail to disclose how to differentiate cylinder temperatures to effectively isolate the firing (power) cylinders from the compression cylinders and from the surrounding environment. In addition, these references fail to disclose how to minimize mutual temperature influence between the cylinders and the surrounding environment. Further, these references fail to disclose engine improvements that enhance conventional internal combustion engine efficiency and performance by raising the firing cylinder temperature and lowering the compression cylinder temperature. Specifically, increasing power cylinder temperature allows for increased energy production, while minimizing compression cylinder temperature allows for reduced energy investment. In addition, the separate cylinders disclosed in these references are all connected by a transfer valve or intermediate passageway of some sort that yields a volume of “dead space” between cylinders. Dead space between cylinders reduces maximum available crankshafts phase angle shift and therefore further degrades the efficiency of the engine. Additionally, none of the references discussed above teach an opposed or “V” cylinder and crankshaft configuration that minimizes dead space and maintains an improved temperature differential between the cylinders through isolation.
U.S. Pat. No. 5,623,894 to Clarke discloses a dual compression and dual expansion internal combustion engine. An internal housing, containing two pistons, moves within an external housing thus forming separate chambers for compression and expansion. However, Clarke contains a single chamber that executes all of the engine strokes. As noted above, a single chamber prevents isolation and/or improved temperature differentiation of cylinders such as those disclosed in embodiments of the present invention.
U.S. Pat. No. 3,959,974 to Thomas discloses an internal combustion engine including a combustion cylinder constructed, in part, of material capable of withstanding high temperatures and a power piston having a ringless section, also capable of withstanding high temperatures, connected to a ringed section which maintains a relatively low temperature. However, elevated temperatures in the entire Thomas engine reside not only throughout the combustion and exhaust strokes, but also during part of the compression stroke. Further, Thomas fails to disclose a method of isolating the engine cylinders in an opposed or “V” configuration to permit improved temperature differentiation and discloses an engine containing substantial dead space in the air intake port connecting the cylinders.
Further, none of the prior art references disclose a split internal combustion engine wherein an electromagnetic interstage valve is biased by an electromagnetically generated biasing force in a closed state.